Check valve



Aug 31 1943- I D. G. GRlsvx/OLD 2,328,010

CHECK VALVE original Filed May 1, 1940 azm/d rllswa/d i9, 70 mi? am @mais Patented Aug. 31, 1943 CEI 2,328,010 v CHECK VALVE' Donald G. Griswold, Alhambra, Calif., assignor to s Clayton Manufacturing Company,- Alhambra,

Original .application May 1, 1940, Serial No.

332,823.- Divlded and this application February 2, 1943, Serial No. 474,447

1o claims. VV(ci. 137-153) The present invention relates to check valves,

.and more particularly to a self-governing check valve designed to operate eillciently and quietly, and to Vopen automatically whenever the pressure on the inlet side of the valve is greater than that on the outlet side of the valve and to close automatically when these pressure conditions are4 reversed.

Qne of the most common objections to known types of check valves is that they have a tendency to slam closed whenever there is an interruption of iiow or change in pressure. Such valves are usually constructed so that the closing member or valve disc, whether it-be hinged or movable bodily, travels in'a direction opposite to that of the normal ilow of iluid to effect closing of the valve; In other Words. the closing member travels in the same direction as the attempted return iiow of iiuid and the inertia of the iluid causes the disc to slam or suddenly strike against its seat. It is this sudden seating,

resulting in the sudden stopping of the movingreturn stream, that sets up a back surge or a ,knock producing what is commonly referred to as "line shock or "water hammer. Aside from the undesirable noiseincident to hammering, there is the more serious danger of the piping burstingfrom sudden excess pressure or-break'- ing as the result of vibratory strains imposed by repeated shock. This situation commonly occurs when a conventional check valve vis used at the end of a long water line. Furthermore,v when such check valve is used at the discharge of a pulsating pump, the valve disc is caused to strike its seat with every pulsation of the'pump, producing frequent and repeated hammerlike blows on the valve disc and seat which quickly destroy member of the present check valve is independent of the back surge or return flow, and contrary to the action of other valves, it does not suddenly fil lthe valve. 'I'he objection and danger increase,

of course, with` the size of the valve.4

In contrast, the check valve of the'present invention is constructed so that, regardless of size, it is impossible for the return Viiow to slam the valve shut and produce hammering or line shock.

While in previous valves, the closing member 1 l has been vdirectly urged against its seat by the attempted return ow and the closing member has thus been caused to travel in the same direc-V ently, the closing member of the present valve i actually cuts oir now bymoving in the same direction as that of the iiuid normally iilowing` through the valve. The operation of the closing cut'oif the return iiow but does act directly thereon, closing slowly and positively at such a. rate as to gradually cut oil the return flow; thereby avoiding damage to the valve and the pipe line.

One important advantage of the aboveaction is that in a. puisatingline, the valve disc or clos,- ing member normally does not'have suillcient time to respond to the rate of ow change and it, therefore, remains partially or fully open With- 'out the disc touching the seat on every pulsatlon desirable advantage, in that it reduces the resistance to the ow of liquid and, therefore, results in lower pumping costs.

Valves constructed in accordance with the present invention operate upon a pressure differential in the inlet and outlet sides of the valve. The valve disc'or closing member of the valve is operated by a diaphragmv which is responsive to the differences in pressure. Means is associated with the outlet chamber of the valve for controlling the rate of ow of the pressure iluid to the diaphragm chamber. 'Ihis control means is arranged so that the valve disc operates at two speeds, i. e., it may move rapidly towardy its seat during the major portion of its travel aiidmove at a comparatively slower rate during the remainder of its travel to effect a generally quick closing and a gradual throttling of the return iiow during the final closing of the valve.

The primary object of the invention is to proi vide a check valve which' will .be free from the above noted objections and which will have the advantage of controlling the flow of water or other iiuid without producing chattering, line shock or hammering. These objections are overcome and the. advantages obtained by providing a .check valve whose clomng action is denitely controlled so as to preclude line shock and hammerlng.

One of the important objects o! the invention is to provide a check valve of the diaphragm type which is automatically responsive to the pressure of the medium passing therethrough and which will close quietly against any'retrn flow with a governed closing action. Y

Another object ot the invention is to provide a check valve which `will close quickly through a major portion of its closing movement and which will complete the closing movement relatively slowly; and further, which can be reopened to its fullest extent without undue delay.

Still another object of the invention is to provide a pressure operated check valve in which Vthe stem of the valve is utilized, in conjunction desired to meet specific conditions; for example,

in certain installations employing large diameter pipe lines of great length and valves of large size, a total closing period of one to two minutes or more may be necessary to cut off ow without i producing line, shock or hammering.

A. further object ofthe invention is to provide a check valve which is positivein its operation and which will not waver or flutter between open and closed positions, but which in normal operation will be either completelyk closed or fully open; complete closing avoiding undesirable leakage through the valve, and full opening enabling the valve to operate with maximum eciency without restricting or impedng ilow therethrough.

A still further object oi the invention is to provide an automatic check valve which is comparatively simple in construction, relatively inexpensive to manufacture, and which requires no substantial servicing.

Other and further objects oi the invention will be apparent from the following description, taken in connection with the accompanying drawing, in which:

Figure 1 illustrates an automatic check valve` of the diaphragm type in which the pressure iluid for operating the valve is taken into the guide stem at a high point on the discharge side of the valve and in which the valve stem is provided with pilot valve means arranged to throttle the admission of pressure fluid into the 'diaphragm chamber toward the end of the movement toward the valve seat to assure a slow closing of the valve and to vpermit relatively quick exhaust of such iiuid to provide for rapid opening of the valve; and

Figure 2 is an enlarged view of the pilot valve shown in Figure l. y

Referring now to Figure 1 of the drawing, the letter B indicates the valve body and the numerals l and 2, respectively, indicate the inlet and outlet sides of the valve. The letter lC4 indicates the cap of the valve and the letter D4indicates a circular diaphragm whose marginal portion is clamped between the body B and the capi c4 by any suitable number of cap screws 3. f

The body B is provided at its inlet side i with a substantially verticalpartition wall portion forming an inlet chamber ia, and an angular wall `portion 5 which cooperate with the wall d to form an oulet chamber 28. The wall portions i and 5 are merged to provide a circular opening@ which is threaded and adapted to receive an annular valve seat The valve seat l is provided with a circular opening 8 which flares outwardly toward the bottom of the valve body as indicated at 9. The upper surface of the valve seat 1 adjacent the opening 3 is provided with a declining beveled portion Ill adapted to cooperate with a valve disc I l to form a leak-proof seal, as will be explained more fully hereinafter. The valve seat I is further provided with circumferential projections 'IB adapted to be engaged by a spanner wrench for tightly securing the seat in the' threaded opening S.

The valve body B has a threaded opening I2 axially aligned with theopening in the valve seat l. An elongated plug I3 is threaded into the opening I2 and includes a tubular guide portion It for one end I5 of a valve stem S4. The cap member C4 also has a recess It counterbored at Il to receive a guide bushing i 8 for the upper end i9 of the valve stem S4. The recess I5 is located in the cap member C4 so that it is axially aligned with the tubular guide portion It and the opening 8 of the valve seat. l

The valve stem S4 has a threaded portion 2d intermediate its lower end i5 and its upper end I9. The end I5 is of slightly less diameter than the threaded portion 2t and has a snug sliding fit in the tubular guide portion Ili of the plug I3. The upper end I9 of said valve stem is enlarged to provide a shoulder at 2l and, moreover, is snugly guided in the bushing it. Thus, the plug I3 and bushing I8 are arranged to guide the stem S4 during vertical movement.

An upper diaphragm supporting plate 22 is adapted to be received upon the stem S4 and to abut the shoulder ZI with the upper side thereof. The upper side of the diaphragm D4 is engaged with the lower side of the plate 22 and is provided with an aperture 23 through which the valve stem S4 extends. is adapted to engage the upper side of a lower diaphragm supporting plate 2li, and the valve stem S4 extends through a central boss 25 in said plate. The lower supporting plate 2t is also provided with a channel 26 formedsin the lower Side thereof to receive the valve disc' I i previously referred to. A combined clamping member and choke washer 28 is adapted to be mounted upon the stem S4 and to engage the inner peripheral portion of the valve disc Il. Clamping nuts 29 are threaded upon the portion 2D of the valve stem S4 and serve to retain the valve stem, the diaphragm supporting plates 22 and 2d, the valve disc I l, and the choke washer 28' in assembled relationv with the diaphragm D4.

The outer diameter of the clamping member or choke washer 28 is preferably only slightly less than that of the' opening 8 in the valve seat l. In a six-inch valve, for example, the minimum radial clearance may be only threeor four-thousandths of an inch. The peripheral portion of the choke washer 28 is preferably rounded, as indicated at 30, and is tapered outwardly and upwardly from said rounded portion to substantially its upper outer edge as indicated at 3l. The rounded and tapered peripheral portions of the choke washer 28 serve to gradually cut 01T the ow through the opening 8, and the beveled portion i of the valve seat 'l cooperates with the valve disc il to reduce eddying and to form a theoretical line-contact seal, whereby quiet, smooth and chatterless operation of the valve is obtained.

The tubular guide il! for the lower end of the valve stern Si is pierced by one or morev transverse openings 32 to establish communication with the outlet chamber 2 of the valve and the interior of said guide whereby the valve stem S4 is 4unrestrained in its movement by any The lower side of the diaphragm D4 threaded into the opening 80 and vided to compress the uid within said guide. The valve stem S4 is provided with a longitudinall passageway 19 which merges into a transverse passagewayv 12 positioned at a point in the stem above the choke washer or clamping member 2l. The clamping member 28' is provided which a screening plug 18 is threaded. The plug 19 contains a screening element 18 adapted to prevent the entry of ,any foreign matter into the passages of the valve stem S4. 'I'he cover C4 is provided with a threaded opening 89 adjacent to the counterbored recess I8'.

an adjustable stop 82 is threadedly mounted in said plug. 'I'he stem portion 83 of said stop member is surrounded by packing 84 and a gland 85 is propacking about said stem to provide a fluid-tight seal therefor.

The stem S4 is provided with an enlarged counterbore 88 atrthe upper end thereof which merges with the longitudinal passageway V1li. The counterbore 88 is threaded at its upper end to receive a collar 89. A pilot or check valve 90 is adapted to be received in said counterbore and to be retained therein by the collar `89. As is clearly shown in the drawing, the pilot valve 90 is provided with 'a depending leg 9| which projects into the passageway 19 and serves as a guide, the size of the leg `9i being such as not to impede the flow of iluid through the passage 10 to an extent such as would prevent quick opening or closing of the valve at the appro- 'priate times.

The exterior ofthe pilot valve 90 is beveled as indicated at 92 and adapted to seat upon the lower inner edge of the collar 89. The pilot valve 99 is further provided with a longitudinal passageway 94 and a transverse passageway 98. Flow through the passageways 94 and 96 of'said valve is controlled by a needle valve 91 threadedly mountedv in the upper end of the pilot valve. A compression spring 98 surrounds the guide 9| of theA pilot valve 90 and normally tends to maintain the valve in seated position. However, the strength of .the spring 98 is such that it does not exert any substantial pressure against the valve to eiect closing thereof, but just suiilcient to overcome the weight of the valve and keep the same closed until the spring is overcome by pressure acting downwardly upon the pilot valve 90 with a `recess 14 intoA A plug 9| isupwardly,and thus, quick opening of the check l valve will be assured in any event.

It will be understoodthat the rate of opening movement of the checkvvalve is greater after the pilot valve 98 has been displaced, since the return ilow of spent iiuid by-passing said pilot 94 and 9B valve is then at a greater rate than normally takes place through the passageways 94 and 96.

'I'he pilot valve 90 will remain in its depressed position and the 'check valve will be wide open until a pressure in excess of the inlet pressure prevails on the outlet side of the check valve. 'I'his same pressure will then exist in the diaphragm chamber 48a and cause the valve stem S4 to move rapidly downwardly to cut oil now through the valve. After the valve stem S4 has moved downwardly a distance suiiicient for the lower edge of the collar 89 Ato engage the beveled' portion 92 of the pilot valve 90, rapid ow of pressure4 fluid to the diaphragm chamber will be cut off and the rate of flow through passageway-s restricted to that afforded by the adjustment of the needle valve 91. In this manner the nal closing movement of the valve is deinitely slowed up.

In avalve of the type shown in Figure 1, lthe portion oi.' the stem-stroke during which relatively slow closing movement is desired can obviously be accurately determined by the adjustment oi' stop 82. Furthermore, the needle valve 91 in pilot valve 99 may be adjusted `to predetermine the rate of travel during said portion of the stem stroke. An. important feature of this type of check valve is that the initial travel of the stein during its opening movement is not necessarily at the` same lrate as the final closing movement, because, as has been pointed out, displacement of the pilot valve 90 andvquick opening of the i check valve may begin before the needle valve 91 actually engages the stop 82.

During both the opening and closing of the vane; the valve disc is guided by the stem s4 or until the head of the needle valve 91 abuts .A

, the fluid in the diaphragm chamber 48a to pressure and while some vof said fluid will back up through the passageways 94 and 98 in the pilot valve 90, the pressure created is normally sufficient to overcome the eifect of spring 98 and force the pilot valve 98 downwardly in the stem S, thereby permitting fluid in larger volume to by-pass the needle valve 91 and exhaust through said valve stem into the outlet chamber 2a. However, in the vevent that fluid pressure does not depress'the pilot valve 90, said valve will be mechanically depressed by engagement of the needle valve 91 with the stop 82 as the stem S4 moves so that it uniformly disengages and contacts the face ci the seat 1. The guiding of the valve disc Il is important, especially during closing, because if the valve disc is not constrained, it will seat upon one side first, and a squeal or a noise comparable to razzing will result as it nallyr seats on the other side and cuts on the now. Moreover,` closing the valve against the flow of the return stream instead of with the direction of such iiow eliminates slam and the hammering incident to sudden checking of the return flow.

-The choke washer 28 also contributes to quiet operation of the valve, in that it cooperates with the opening 8 in the valve seat to gradually restrict the ow and substantially cut it oil? just before seating of the valve disc Il occurs, thereby eliminating any tendency of the valve disc to flutter. .p '."Iius it will be apparent that a two-speed check valve has been provided which is automatic and self-governing in its operation and which has the highly desirable advantage of quick opening and substantially quick closing, but whose nal closing movement is regulated so as to eliminate sudden closing of the valve with its accompanying hammering and line shock. i

The present application is a division of my copending application Serial No. 332,823, filed May 1, 1'940, and entitled Check valves.

It will be understood that the principles of the invention lmay be embodied in valves different from that illustrated herein without departing i from the spirit of thefinvention and the scope of the appended claims.

I claim: y 1. In an automatic check valve comprising a body having inlet and outlet chambers, a dia-I phragm for controlling the ow from said inlet chamber to said outlet chamber and a pressure chamber for operating fluid for said diaphragm;

a valve stem connected'to said diaphragm, said.

valve stem having a passageway in continuous communication with said outlet vchamber and said pressure chamber; and spring-pressed means in said passageway carried by said valve stem for controlling the rate of iiow therethrough, said means having a passageway therethrough smaller in size than said passageway in said valve stem.

2. A self-governing check valve comprising, a`

body: a flexible diaphragm for controlling the iiow of fluid through said body; a pressure chamber for operating fluid for said diaphragm; a valve stem connected to said diaphragm, stem having a passageway in continuous communication withl said body and said' pressure chamber;- and a pilot valve iioatingly mounted in said passageway of said valve stem for. controlling the rate of flow of fluid through the passageway of said stem, said pilot valve having a passageway therethrough smaller in size than said passageway in said valve stem.

3. A self-controlled check valve, comprising: a body having inlet and outlet chambers; a diaphragm for controlling the flow of fluid from said said valve inlet chamber to said outlet chamber; a pressure chamber for operating fluid for said diaphragm; a valve stem connected to said diaphragm, said valve stem having a passageway communicating with said outlet chamber and said pressure chamber; a pilot valve in said passageway for controlling the flow therethrough, said pilot valve having a passage; and means for varying the rate of flow of fluid through the passage of said pilot valve.

4. A' self-governing check valve, comprising:v a

body having inlet and outlet chambers; a diavalve stem starts to move phragm,

phragm for controlling the oW of fluid from said inlet chamber to said outlet chamber; a pressure chamber for operating iluid for said diaphragm; a valve stem connected to said diaaction, comprising: a body having inlet and outlet chambers; a diaphragm for controlling the flowof uid from said inlet to said'outlet chamber; a pressure chamber for operating fluid for saiddiaphragm; a valve stem adapted to reciprocate in saidbody; phragm to said valve stem, said valve stem having a longitudinal passageway in communication l with said outlet chamber and said pressure chamber; a pilot valve mounted in one end of said v valve stem; a spring normally maintaining said pilot valve in closed position. said pilot valve havsaid valve stem having a passageway l vcommunicating with said outletchamber and means connecting said dia-4 ing to said outlet opening; for operating fluid for said ,connected to said means, said valve stem having `a passageway in continuous communication with one of said openings and with said pressure ing a restricted passageway therethrough in cornmunication with said pressure chamber and the longitudinal passageway in said valve stem; and a needle valve arranged to control the iiow through the restricted passageway in said pilot valve to said pressure chamber. Y

6. A check valve comprising: a body having inlet and outlet chambers; a cover phragm for controlling the fl'ow of uid from said inlet to said outlet chamber; a pressure chamber for operating fluid for said diaphragm; a valve stem adapted to reciprocate in said body; means in said body for guiding said valve stem; means connecting said diaphragm to said valve stem comprising a clamping member and'supporting plates arranged on opposite sides of said diaphragm, said clamping -member having a passage extending therethrough and said valve stem having a transverse and a longitudinal passageway in communication with the passageway in said clamping member; a pilot valve mounted in one end of said valve stem; a spring normally maintaining said pilot valve inclosed position, said pilot valve having a restricted passageway therethrough in communication with the longitudinal passageway in said valve stem and said 4pressure chamber; and a stop member carried by said cover plate and adapted to be Aengaged by said pilot valve and to open the same upon a given opening movement of said valve stem.

7. An automatic lcheck valve, comprising: a body having' inlet and outlet openings; means for controlling the flow from said inlet opena pressure chamber means; a valve stem chamber; and check valve means in said passageway carried by said valve stemA for controlling the rate of flow therethrough', said check valve said pilot valve'having u 5. A check valve having a controlled closing y for controlling the having a passageway therethrough smaller in size than said passageway in said valve stem.

8. A self-controlled check valve comprising: a body having for controlling the flowA of fluid from said inlet opening to said outlet opening; a pressure chamber for operating fluid for said means; a valve stem'connected to said means, said valve stem having a passageway communicating `with said outlet opening and with said pressure chamber; a pilot valve in said passageway for controlling' the ow therethrough, said pilot valve having a passage; and means for varying the rate of flow of fluid through the passage of said pilot valve.

9.l A self-governing check valve, comprising: a body having inlet and outlet openings; means iiow of uid from said inlet opening to said outlet opening; a pressure chamber for operating fluid for said means; a valve stem connected to said means, said valve stem having a passageway communicating with said outlet opening and said pressure chamber; a

reciprocable pilot valve in said passageway, said I pilot valvehaving va relatively restricted passage extending therethrough f or the passage of iiuid from said pressure chamber at a slow rate; and

means arranged to unseat said pilot valve after move toward open posivalve will be held open said valve stem starts to tion, whereby said pilot and iiuid can by-pass said pilot valve and flowfrom said pressure chamber at a relatively higher rate to permit a quick opening of the valve.

10. A check valve comprising: a bo'dy having' inlet and outlet chambers; a'diaphragm for conplate; a diainlet and outlet openings; means ed to reciprocate in said body; means connecting said diaphragm to said valve stem comprising a supporting plate and a clamping member below said supporting 'plate on one side ofsaid diaphragm and .a clamping plate on the other side valve l.stem-having a transverse and longitudinal passageway incommunication with the passage,-

vway in said clamping member; and a pilot valve l mounted in one end oi' said valve stem for con` trolling the iiow of iluid through said valve stem, said pilot valve having a restricted passageway therethrough in communication with the'longi- -tudinal passageway in said valve stem and said of said diaphragm, said clamping member hav-A ing a passage extending therethrough and said 10l pressure chamber. y A

' lDONALD G. GRISWOLD. 

